I find that I agree with you. It's not easy to decide when and if a post should be deleted.
In time you begin to recognize the precursor to a posting melee and you want to stop it before it starts. That might mean deleting a post or two that in and of themselves weren't terrible but just edged up to the line. Sort of like sensing the pot is ready to boil over and turning down the heat before it actually does.
A gentle private message explaining why the post was removed can be good as well. Perhaps posters will come to learn more clearly where the line is and steer away from it.
Anyway, as I used to say on RB, 2 cents from a 3 dollar poster.
PS to Matt - Why isn't "melee" in your dictionary?